1. Technical Field
The present disclosure relates to the electronics field. More in particular, the present invention concerns a voltage regulator with by-pass capability for test purposes.
2. Discussion of the Related Art
A voltage regulator may be an electronic device designed to receive an input voltage and to generate therefrom a regulated output voltage at a constant voltage level, despite fluctuations of the input voltage and despite a variable output load.
A voltage regulator is integrated into a system-on-chip, wherein the regulated output voltage is used as a supply voltage for electronic components inside the system-on-chip.
A common linear voltage regulator for providing a regulated output voltage smaller than the input voltage is composed of a controller and of a transistor (such as a BJT or a MOS), wherein the controller is such to generate a control signal driving the control terminal (base for the BJT or gate for the MOS) of the power transistor and wherein the power transistor is interposed between the input voltage and the output voltage. A power transistor separate from the controller is used in case the transistor requires an high power dissipation.
In the automotive field, a voltage regulator within a system-on-chip is needed, for example, for providing a regulated supply voltage to a memory within the system-on-chip; in this case it is necessary to ensure an high safety of the system-on-chip and thus it is necessary, before delivering the system-on-chip for selling, to perform the test of the operation of the electronic components inside the system-on-chip with the voltage regulator disabled at the start-up of the test, in order to be able to supply the electronic components inside the system-on-chip with a test supply voltage greater or smaller than the nominal value of the output low supply voltage.
A known solution for disabling the voltage regulator at the start-up of the test is to force the regulated output voltage to an higher value, so that the current source inside the voltage regulator is switched-off; afterwards, the overall voltage regulator is disabled (by means of software or JTAG protocol) and finally the output voltage is forced to a lower value required for performing the test. This solution has the disadvantage to require a too long time for disabling the voltage regulator, because it requires some time in order to stabilize the output voltage at the wanted value for the test.
Moreover, some known solutions to disable the voltage regulator at the start-up of the test have the disadvantage of needing the generation of complex sequences of values of several signals, which are also different between the switch-off and the switch-on phase.